Drafting appliance



Aug. 9, 1949. 'r. A. DE POSTELS 2,478,751

DRAFTING APPLIANCE Filed Aug. 25, 1945 6 Shets-Sheet 1 ATTORNEYS Aug. 9, 1949. T. A. DE POSTELS 78,

DRAFTING APPLIANCE Filed Aug. 25, 1945 6 Shets-Sheet 2 69 %2 33 J/'J3' a z a 5 30 i z E zg/mvizvroR.

29 ATTORNEYS A 9, 1949- T. A. DE POSTELS 2,478,751

DRAFTING APPLIANCE Filed Aug. 25, 1945 v 6 Sheets-Sheet 3 45 4 2 6 g @g 7 Ri a- JNVENTOR.

BY I "fimpfwwzw ATTORNEYS Aug. 9, 1949. T. A. DE POSTELS 2,478,751

DRAFTING APPLIANCE Filed Aug. 25, 1945 GShets-Sheet 5 IN VEN TOR.

ATTORNEYS Aug. 9, 1949.

T. A. DE POSTELS DRAFTING APPLIANCE 6 Sheets-Sheet 6 Filed Aug. 25, 1945 I INVENTOR.

ATTORNEYS Patented Aug. 9, 1949 UNITED STATES PATENT OFFICE DRAFTING APPLIANCE Theodore A. de Postels, New York, N. Y.

Application August 25, 1945, Serial No! 6 2,627; 3 o1aim,.- (o1. a'a-nm This invention relates. to drafting appliances and p r lar-1y to improvements in ppliances for use in making p rspective drawings. In general this invention may be regarded as constituting improvements in drafting appliances of the ype claimed in my Patents No 1,657,301; of January 2i,v 1928 and No. 1,807,237 of May 26, 1831, the, improvements relating principally to the construction and mechanical interconnection of various parts of such drafting appliances.

It is an object. of this invention to provide rulers. uiding, directing and indicatin mem bers of improved construction and improved means for interconnecting such members whereby accurate perspective drawings can be made with a minimum of effort in the shortest possible time.

In general the invention claimed in my Patent No. 1,657,301 includes rulers for use. in drawing the lines, which, if extended, pass through the vanishing points, another ruler cooperating with the rulers just mentioned and adapted to indicate true heights of the object, and directing and indicating devices for use in determining the positions oi the points and of the vertical lines of 1 1e perspective drawing.

In general the invention claimed in my Patent No. 1,807,237 includes improved means for interconnecting rulers, guiding, directing and indicating members of improved construction, comprising separate fixed, adjustable and automatically sliding members, this invention being useful not only for making linear perspectives but also for the purpose of making curvilinear, relief, theatrical and radial erspectives, and in pantographic work.

One of the features of the present invention comprises the combination with a drawing board of ordinary construction, of a sheet of rigid ma tcrial extending over a substantial portion of the drawing board. I provide detachable means for securing marginal portions of this thin sheet of material to the drawing board in such a manner that the majorportion of the thin sheet is pac from the drawing board to accommodate a (iirector member loosel mounted between the th n sheet and the drawin board, as hereinafter ex piained in reater detail. A sheet of. ordinary drawing paper maybe secured to the thin sheet of r gi material mounted on the. drawin board in'the mann r iust described This. feature is of nartioiuar value because the ireed m. of mo e ment over the area Where the desired drawin is to be made is in no way encumbered or intere fered with by the director member. which is cop 2. cealed from View and entirely out of the way of the draftsman except. tor the upperextremity thereof which is utilized in indicating and directing the. location or points and lines to be filled, in on the perspective drawing.

Another feature of my invention is the provision of interconnecting attachments for the several T-squares or rulers members, whereby T-square and ruler members can be employed without the necessity for providing slots or other openings through these members at the points Where they intersect. My improved interconnecting ele ments are provided with complementary slots. oropenings, and guide pins. arranged so that a vertical edge of the guide pin carried by one; of these connecting pieces is in line with a marginal edge. of each of the two ruler members interconnected by these elements. Thisieature of my invention permits perfect visibility, and therefore maximum precision in adjusting the director member to any desired point or line. The interconnecting pieces having the comple tary o p ratin pins and openings. are preferabl each provided with two sets of these complementary elements so that either side of any ruler member may he.v selected at will as the working edge or side or this member as may be desired by thedraftsmam and the connecting pieces are so formed that; a simple manipulation requiringonly a moment is all that is required in order to shift from one Working edge of a ruler member to the other to suit the convenience ofthe draftsman in Working on difierent portions of the drawing.

Another feature of my invention is the provision of detachable end plates for certain oft-he ruler members whereby they may be pivoted at any desired point on th drafting, board or on an auxiliary support, the construction of, these end plates r m nts being such that the. pivoted ruler membermay swin around the pivo p in with either marginal edge of the ruler member in alinement therewith, as may be desired. These end pieces may be provided with a. number of openings orprojections permitting a. variety of adjusted relative positions of th ruler member with rmpect to the pivot attachment of the en pieces to the drawing boardor other support therefor.

Another feature of. my invention resides in the improved construction of a. sliding adapter member provided with freely moving pulleys ior' enseeing and guiding one marginal edge of: a ruler member while the other edge of this ruler memher is maintained in firm contact with a pivot pin.

My invention also includes as a part of the apparatus for making perspective drawings a rotatable disk suitable for showing the working plan view in such manner that the plan view can be adjusted to any desired angular position with respect to the picture plane. This makes it unnecessary to prepare a new plan drawing whenever it is necessary or desirable to change the angle to the picture plane. The rotatable disk carrying the plan view may comprise a sheet of cross section paper and it may be mounted so that it may be fixed in any desired position. I prefer to employ a center pivot pin fixed with respect to the drawing board and engaging the rotatable disk, this pivot pin being located at the intersection of the vertical center line and the horizontal picture plane. Other features of my invention include the provision. of a double band of strip material having a fiatheaded pivot pin projecting through one strip and serving as a pivot support for the director element. When this double band pivot pin support is used, the director element is supported thereon out of contact with the drawing board. If desired, a number of adjusting brackets associated with clamping elements near the edges of the drawing board may be provided for supporting the double band in any desired adjusted position.

I may also employ a single bar of smooth, preferably transparent material extending across the drawing board in the vicinity of the horizontal picture plane line and providing a smooth supporting surface for the connecting pieces associated with the director element and the vertical T-square or ruler member.

The various features and advantages of my invention will be apparent upon considering the following detailed description of certain illustrative embodiments thereof shown in the accompanying drawings, in which:

Fig. 1 is a plan view showing one embodiment of my improved perspective drafting apparatus;

Fig. 2 is an enlarged transverse section View taken on line 2-2 of Fig. 1;

Fig. 3 is an enlarged longitudinal section view taken on line 33 of Fig. 1;

Fig. 4 is an enlarged fragmentary section view taken on line 4--4 of Fig. 1, showing details of construction;

Fig. 5 is an enlarged transverse section view taken on line 5-5 of Fig. 1 illustratin the construction of two of the connecting pieces;

Fig. 6 is an enlarged elevation of the rotary disk pivot means;

Fig. '7 is an enlarged fragmentary view of the drawing board corner plate illustrated in Fig. 1 and showing means for attaching the drawing board to a suitable support;

Fig. 8 is an enlarged side elevation of one of the clamping elements forming a part of the apparatus of Fig. 1;

Fig. 9 is an enlarged plan view of the end connecting piece forming a part of the apparatus of Fi 1;

Fig. 10 is an end elevation of the end piece illustrated in Fig. 9;

Fig. 11 is a plan view of a connecting piece forming part of the apparatus of Fig. 1;

Fig. 12 is an end elevation of the connecting piece of Fig. 11;

Fig. 13 is an end elevation of another connectifing piece forming a part of the apparatus of Fig. 14 is a plan view of still another con- 4 necting piece forming part of the apparatus of Fig. 1;

Fig. 15 is an end elevation of the end piece illustrated in Fig. 14;

Fig. 16 is an enlarged plan View of one end of a director member forming a part of the apparatus of Fig. 35;

Fig. 17 is a fragmentary elevation of a portion of the director member of Fig. 16 assembled with a connecting piece;

Fig. 18 is a fragmentary elevation of one of the ruler members forming a part of the apparatus of Fig. 25;

Fig. 19 is a plan view of the element illustrated in Fig. 18;

Fig. 20 is a side elevation of a guide member forming part of the apparatus of Figs. 1 and 22;

Fig. 21 is an end elevation of the guide member illustrated in Fig. 20;

Fig. 22 is a plan view showing another embodiment of my improved perspective drafting appliance in which many of the parts are the same as corresponding parts in Fig. 1;

Fig. 23 is a fragmentary elevation, partly in section, illustrating a detail of one of the fastening devices employed in Fig. 22 taken on line 2323 of Fig. 22;

Fig. 24 is an enlarged plan view of a connecting piece forming a part of the apparatus of Fig 22;

Fig. 25 is a plan view of another embodiment of my invention in which many of the parts are similar to corresponding parts of the apparatus illustrated in Figs. 1 and 22;

Fig. 26 is an enlarged plan view of a connecting piece forming a part of the apparatus of Fig.

Fig. 27 is an end elevation of the element illustrated in Fig. 26;

Fig. 28 is a plan view of another connecting piece forming a part of the apparatus of Fig. 25;

Fig. 29 is an end elevation of the element illustrated in Fig. 28;

Fig. 30 is an enlarged elevation of an auxiliary adapter block forming part of the apparatus illustrated in Fig. 25;

Fig. 31 is a plan view of still another embodiment of my invention;

Fig. 32 is an enlarged transverse section view taken on line 32-32 of Fig. 31;

Fig. 33 is a fragmentary section view of a portion of the apparatus illustrated in Fig. 1;

Fig. 34 is an enlarged elevation of the pivot pin forming a part of the appartus of Fig. 31;

Fig. 35 is a plan view of still another embodiment of my invention;

Fig. 36 is an enlarged detail section view taken on line 36-36 of Fig.35;

Fig. 37 is an enlarged detail section view taken on line 31-31 of Fig. 35;

Fig. 38 is an enlarged detail section View taken on line 3838 of Fig. 35; and

Fig. 39 is an enlarged detail section view taken on line 39-49 of Fig. 35.

In the illustrative embodiment of my invention shown in Figs. 1-19, inclusive, of the drawings.

I have illustrated at I a drawing board which may be of any suitable dimensions and construction except for the provision of guides or tracks 2, 3 and 4 extending along portions of the side edges of the board and along the bottom edge, and except for the provision of corner plates 5 and 6 of metal or the like. The track members 2, 3 and 4 may be made of metal or other suitable arm-rm;

material and permanently secured to: the ed es ofi boa-rd Ii anysuitable way; Eoclr track is provided'wirh a; longitudinal groove: adapted to receive a; downwardly projectin flange: of a slide membersuch asthe one: illustrated at. t and Figs. 2d and 2 1 The corner plates 5 and 6 maybe permanently secured to the corners: oi iboazrdl I in any: suitable: manner and these comerpl'ates are provided with: openings 8% for accommodieting tacks, nails: or screws, by means ofiwhiohz the drawing: board: may be firmly secured to" any" desired support as a. drafio ing'table;

An important teams or my resides provision; of a sheet of 9 (amending over a substantial portion of; the. drawmg board I: but spaced therefrom marginal strips to. H and t2 fiastenedi to the drawing board; by screws; or like serve to a. bar or" strip oi transparent maternal. tit" upper corners or sheet no rigidi ma.- terial. 8 in; proper position, and: the lower corners of. the sheet may he; scarred in place by tacks E3 and ti, The rigid sheet 9 may be: of a. moisuitable for drawing thereon the. desired perspective view: but it it is desired to make the perspective view on an: ordinary sheet or drawmg paper; such. a sheet? l5 may be. secured to: the upper surface: of the rigid sheet El by any suitable means such as small. strips or tape to.

- The appartueas i'llustrated'fn. Fig. 1 in.- clnudes' a rotatable k'i or thin sheet" preferably cross section paper. A central fiat-- pin. Id (best shown in Fig. 3) may be glued; or otherwise attached to the. center ozfi the rotatable disk H, the head of the pin projecting inter an opening in the drawing board: I,. pro:- v'l'decl: tor this purpose. This pivot pin may he locatedet the intersection of the vertical comer line: with the horizontal picture: plane and will be understood that the; plan view n the obieet may be drawn on the rotatable disk ll as illustreated at A- Fig. 1.. The elevation view of the objeet'may on. the sheet of material ll or on the drnmrrg paper is superimposed thereon as shown at B.

Inv making the perspective drawing, the usual procedure may be followed, according to whim: the plan. View A located near the upper portion of the drawing board, and. because of the. fact thatithis plan view may drawn on the rotatable disk. element i! it. will be understood that the: angular position. of the plan view may be readily adjusted tozmy desired angle. The elevation B is. located near one side of the drawing board andithe line a representing the picture plane passes'through the pivot point of the rotatable disk H. The vanishing points b and c are determined in the usual way by drawing lines at and e from obser ation point 1 parallel with the adjacent side edges of the plan view A until these lines intersect the picture plane, and then dropperpendiculers from. these intersections to line g arbitrarily chosen to represent; the line of elevation of the observers eye. The perspective plane of any vertical edge of the. object may be determined in the ordinary manner as explained, for example, in my prior Patent 15513361.

A director member is in the form of ruler having beveiled edges is mounted between the sheet of rigid material 5 and the drawing board I, the lower end of this director member being carried by an end connecting piece 20 (see Figs. 3, .9. l0 and 1'2) having openings 2t and 21' thereinior accommodating a thumb tack 22 by means 6. of the directormember'lfil may-' be 1on chored to the drawing boardisoas to swing: about the. observation point. fr, the thumb-tack 2Q being located; at this observation point. The openings: 2t and: 2;! are symmetrically. disposed at eithersid'e: or the connecting piece 25 in alogn-mentwith the side edges 01% the director member $59 so: that. by selecting either one. orthe other of these. openings 2| and 21s" .forpivoting the: director member; corresponding side edge. or the or rectormember can be employed; as: the working edge-to broughitdntoz alignment with any'selecs todipcint on the plan view A to. determhre the desired corresponding point in the perspective. View. Thus, when the. director member pivots about. the openingv 215, the left edge. or the director member may be used: the working edge cooperating with the plan view A: and when the right. hand opening 25 isusecl as the pivot. the. right hand edge of the director mama her my be. employed as: the working co operating'witlfiz the: plan View A. i

The connecting: piece 20 is provided with apair or Z3 and 23' adapted to engage correspond openings inthe director member 19, as: illostrated in Figs 1 and 1- 7, and connecting piece. is: provided with a of lugs 24 and 24 for engaging the lateral edgesof the director member whereby the director member l9 and the connecting piece 28 are held in firm inter-em gagement. The connecting piece 20, having the openings Zl and Zf'f atthe lower extremity thereof, as explained above, may also be provided auxiliary round openings 25 and 25" of somewhat larger diameter to accommodate a pivot pin of corresponding size.

The openings Hand 2|" are in alinement with the side edges of the director member but the openings zi and 25' are located somewhat. farther apart so that the inner portions thereof are in alinement with thesidie edges, of the. director memben The connecting. piece. 20. may be providedwith additional auxiliary openings of sectori'af shape suchas. those illustrated at 26. and 28 adapted to receive a. sectori'al pin having its angular edge in alinement with the side. edges oi the director member.-

.A vertical ruler member 21 (Fig. 1). is carried. by a guide piece as having a flange engaging. the slot in the lower track member 3.. Connecting pieces 29 and. 39 serve to interconnect the. ver tical ruler member 21. and. the. director member [a as best. illustrated in Fig. 1. As illustrated in Figs. 14 and 15, the connecting piece 30.. is provided with a central pin or projection 3!:- adapted to engage any selected one of said. corresponding openings. 32 in the vertical ruler memher 21, lugs 33 and 33' being provided the connecting piece for engaging the lateral edges of the upper end of the vertical ruler member 21. This connecting piece 36 is also provided with a pair of seetorial openings 34 and 34" adapted to selectively accommodate a sectorial pin 35 in the connecting piece 23 (Figs. Hand 12). It will be understood that when the interconnecting vertical-ruler member 2! and the. director member la are simultaneously moved until the working edge of the director member is in alinement with some selected point of the plan view A, the corresponding working edge of the vertical ruler member indicates a, corresponding portion of the perspective drawing, the exact lo; cation of which is determined by a horizontal ruler member 36 (Fig. 1) carried by the guide piece I so that it can be moved to the corresponding location on the elevation B.

The guide piece 1 which carries the horizontal ruler member 36 is provided with an arc shaped slot 1a having a lateral extension lb and with an opening 10 (see Figs. and 21) to accommodate the clamping bolts Id and 1c. The arrangement is such that by loosening the nuts on the bolts Id and 1c, the ruler member 36 can be adjusted to any desired angular position and the lateral slot lb is so located that when the bolt 1d engages this lateral slot, ruler member extends at right angles to the edge of the drawing board.

This horizontal ruler member cooperates with another ruler member 31 pivoted at the vanishing point 0 by means of a connecting piece 38 which may be carried by an auxiliary support 39 mounted either on the drawing board or at some point near the edge of the drawing board, depending upon whether the vanishing point e is located at a point on the main drawing board or at some point laterally displaced therefrom as best illustrated in Fig. 1. The connecting piece 38 may be provided with several openings and pivot pins located and arranged as previously described in connection with the connecting elements of Figs. 9l2, inclusive, it being understood that in each instance the round or sectorial pins are adapted to engage either selected side of the corresponding ruler member in exact alinement with the selected working edge thereof.

Connecting pieces 40 and 4| provided with cooperating sectorial openings Ma and 41b and the sectorial pin 40' serve to interconnect the horizontal ruler member 36 and the ruler member 31- as best illustrated in Figs. 1 and 5. The sectorial pin 40' is carried by the connecting piece 40 and the sectorial openings 4| a and MD in the connecting piece 4| are arranged at the outer side thereof so that by merely reversing the connecting piece 40, the sectorial pin 40' will register. with the sectorial opening adjacent the other edge of ruler member 31. Thus either edge of this ruler member may be used as the working edge by merely shifting the connecting piece 38 and reversing the connecting piece 40.

Fig, 22 shows certain features of my invention arranged for pantographic work. Many of the elements previously described in connection with Figs. 1-17, inclusive, 2n and 21, are employed in the arrangement illustrated in Fig. 22 wherein they bear the same reference characters as in the figures previously described. Referring to the additional elements employed in Fig. 22, I have illustrated at 42 what may be characterized as a slotted pin holder which may be clamped in an adjusted position so that the director member I9 will pivot about a pin 43 (see Figs. 18, 19 and 22) carried by the pin holder 42. The guide rail or track 2 at the edge of the drawing board is provided with openings to receive adjusting bolts 44 and 45, the bolt 44 being adapted to register with the slot 46 in the pin holder 42. A slotted bracket 41 carrying an adjusting bolt 48 is adapted to engage the bolt (Fig. 23), the arrangement being such that by loosening nuts on the bolts 44, 45 and 48, the pin holder 42 may be adjusted to any desired position and clamped in) tins position by tightening the nuts on these 1 Fig. 22 shows a plan view A on the disk I1, located at a point above the pin 43 and the director member I 9' and the vertical ruler member 21' connected thereto through the connecting pieces 29 and 30 may be utilized in drawing a second plan view A" on the disk I! on a different scale from that employed in drawing the upper plan view A, the respective scales being proportional to the respective distances of the upper plan view A from the pin 43 and the distance between this plane and the line representing the picture plane, as indicated by the arrows in Fig. 22. These plan views may be used in drawing pantographic perspectives, enlarging. or diminishing the scale of the perspective view in various proportions. The pin holder 42 is preferably beveled as indicated in dotted lines in Fig- 22 and as shown in Figs. 18 and 19.

The director member [9' is held in engagement with the pivot pin 43 carried by the holder 42, by means of a sliding connecting piece 49 having openings 49 and 49" at either side thereof (Fig. 24) for accommodating the pin 43. It will be understood that either edge of the director member 19' may be used as the working edge by merely shifting this member so that the appropriate opening in the connecting piece 48 engages the pin 43 and by shifting the connecting pieces 29 and 30 so that the pin of connecting piece 28 engages the opening 34 of connecting piece 3| (Figs. 11, 12, 15, 16 and 22).

Fig. 25 illustrates another element of my invention in which many of the parts are identical with those previously described. In Fig. 25 the auxiliary supporting member 39 is shown at a location above the drawing board where it may be supported on the same table or other support used for holding the drawing board. Two slotted pin holders 42 and two slotted bracket members 41, located one on either side of the drawing board, serve to locate a station point pin S carried by the auxiliary support 39 with respect to the drawing board I. A director member I!" is detachably secured to a connecting piece 50 (Fig. 28) having a plurality of openings 50 at either side thereof for accommodating the station point pin S so that either edge of the director member l9" can be used as the working edge in alignment with the station point pin, as may be desired.

The director member 19" is connected to the vertical ruler member 21 by means of connecting pieces 29' and 30, the connecting piece 29' being similar to that illustrated in Fig. 13 and the connecting piece 30' being illustrated in detail in Figs. 26 and 27 which show this element as connecting pins 30a and 30'b for engaging the sectorial openings in the connecting piece 29. The

- connecting piece 30' has a center projection 5| adapted to engage any one of several openings in the vertical ruler member whereby this connecting piece may be detachably secured to the vertical ruler member to locate the pin 30'a or the pin 30b at the picture plane line, depending upon which edge of the director member is to be used as the working edge.

In Fig. 25 the circular disk I! and the thin rigid plate 9 shown in Figs. 1 and 2 are not employed, and the sheet of drawing paper I5 is secured directly to the surface of the drawing board. The arrangement as illustrated in Fig. 25 is particularly useful for pantographic work.

The connecting piece 50 at the upper end of the director member I9" in Fig. 25 may be secured thereto by means of a bolt and detachable nut as shown at 52 in Fig. 29.

The arrangement illustrated in Fig. 31 comprises a drawing board, vertical ruler member 21, director member l9, slotted pin holder members 42 and brackets 41, all similar to the corresponding elements described above in connection with other figures of the drawings. In Fig. 31, as in Fig. 25, the drawing paper I is fastened directly to the drawing board. A modified pivot support for the director member I9 is illustrated in Figs. 31-34, inclusive, this support comprising two strips of thin flexible material 53 and 54 riveted together at the ends as shown at 55. The upper strip 53 is provided with a series of openings to accommodate the pins 43 and 43 of the slotted pin holders 42 and to accommodate a center fiat headed pin 59 which may be located at the observation point. The pin supporting strips 53 and 54 may be held in any desired adjusted position by the pin holder members 42 which may be clamped firmly in place by means of the bolts 44 and 45 and the slotted brackets 41 as previously described.

The pin holding strips 53 and 54 may extend over the upper surface of the vertical ruler member 27 as clearly shown in Figs. 31 and 32 so that this ruler member may be moved freely back and forth across the drawing board surface without interfering with the observation point pin 52 or with the pin holder members 42 disposed between the two strips 53 and 54. It will be understood that the strips 53 and 54 are sufliciently flexible so that they can be separated to insert the pins 43 and 56 and then the strips 53 and 54 can be held firmly in position by adjusting the brackets 41 and the bolts 44 and 45.

Fig. 35 shows still another arrangement of some of the mechanisms described above with certain added parts to provide a drafting appliance particularly suited to the purpose of making perspective drawings with a large view distance, the distinguishing feature of this appliance of Fig. 35 being the use of what may be characterized as a director mechanism employing a director ruler 19a firmly secured to the members I9b and 190 having sliding engagement with the pins 43 of the pin holders 42. The lower end of the director ruler member l9a is provided with several openings 68, 69 as best illustrated in Fig. 16, to accommodate bolts 51 and 58 passing through are shaped slots in the enlarged ends of the director members I91) and 190 as best illustrated in Figs. 35 and 36.

A third bolt 59 passing through center openings in these enlarged ends of the members l9?) and I90 serves to clamp these two members firmly together, and it will be understood that when the nuts on the bolts 51, 58 and 59 have been tightened, the director mechanism comprising the roller member 19a and the members 19b and I90 may be moved as a unit with the members I91) and 190 in sliding contact with the pins 43 of the slotted pin holders 42. The members I91; and l9c are held in engagement with the pins 43 by adapter members 60 as best illustrated in Fig. 37.

In Fig. 35 I have also illustrated a modified form of adapter member 38' pivoted on the pin carried by the auxiliary supporting piece 39. As best illustrated in Fig. 39, this adapter member 38' carries a pair of loosely mounted rollers 6| each supported by a bushing 62 mounted on bolts 63. The bushings 62 are of somewhat greater length than the roller members, and accordingly when nuts 64 are tightened, the roller members remain free to rotate as the ruler member 31 is moved back and forth.

In Fig. 35 the ruler members 35 and 31 are connected by the connecting piece 29 having a pin 10 35 projecting therefrom as best illustrated in Fig. 38. The pin 35 may register with any one of several openings provided in a connecting piece which may be detachably secured to the ruler member 3? by means of a bolt 65 and nut 61.

The arrangement of Fig. 35 is such as to provide maximum freedom of movement of the various ruler members with the least possible obstruction of the Working areas on the drawing board. This mechanism may be used in making large perspective views employin plan and elevation views of correspondingly large dimension, and in this connection it will be noted that the sheet of drafting paper I 5" shown in Fig. 35 covers substantially the entire surface of the drawing board I.

It will be understood that my invention is not limited to the particular embodiments thereof illustrated in the accompanying drawings, but includes such modifications thereof as fall within the scope of the appended claims.

I claim:

1. In a device of the type described comprising a ruler, a connecting piece thereon, a pivot pin carried by said connecting piece, and a second ruler engaging said pivot pin, the improvement which consists in having said pin formed with a vertical sharp edge in line with a marginal edge of said first ruler and engaging a marginal edge of the second ruler.

2. in a device of the type described comprising a pair of ruler members and connecting pieces for interconnecting said members, the said connecting pieces being carried by the ruler members, the improvement which consists in having one of said pieces provided with a sectorial opening therethrough and the other piece provided with a sectorial pin fitting in the sectorial opening with an edge of the pin in line with a marginal edge of one of said rulers and engaging a marginal edge of the other ruler.

3. A device of the type described comprising a pair of ruler members having upper and lower marginal edges, a pair of connecting pieces for interconnecting said ruler members, the said connecting pieces being carried by the ruler members, one of said pieces having openings therethrough at either edge thereof and the other piece having a pin fitting either opening whereby the pin may be either in alinement with the upper marginal edge of one ruler member and engaging the upper marginal edge of the other ruler member or in alinement with the lower marginal edge of one ruler member and engaging the lower marginal edge of the other ruler member.

THEODORE A. DE POSTELS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 931,080 Perris Aug. 17, 1909 1,551,501 Hurlburt Aug. 25, 1925 1,657,301 De Postels Jan. 24, 1928 1,807,237 De Postels May 26, 1931 1,920,959 Clementi Aug. 8, 1933 1,986,625 De Lorenzi Jan. 1, 1935 1,994,401 Muziczka Mar. 12, 1935 2,082,802 Karnes June 8, 1937 2,413,376 Pomeroy Dec. 31, 1946 

